1. Field of the Invention
This invention relates to the field of optics. More particularly to the use of soft contact lenses to improve human sight and most particularly to an apparatus for killing germs, bacteria, and viruses which might contaminate such lenses.
2. Description of the Prior Art
Soft contact lenses are made from a hydrophilic material. Hence, they absorb liquids, particularly human tears. This, plus their being held in contact with the eye and thus being sustained at the external temperature of the eye makes them a potential source of infection by absorption and growth of pathogenic microorganisms. The lenses should be made clean and aseptic between wearing intervals.
Presently, users of soft contact lenses asepticise them by one of two methods. One method is to immerse them in an antiseptic solution; hydrogen peroxide, for example. After soaking in the antiseptic, the lenses are repeatedly immersed in sterile water or saline solutions until enough of the antiseptic is removed from the lenses as to pose only a minor hazard to the human eye. A second method generally proceeds as follows: the soft contact lenses are immersed in a saline solution inside a container. The container is then sealed against fluid flow. The container is next immersed in steam from water boiling in an unsealed vessel. The temperature of the steam on the outside of the lens-holding container is generally at or below 212.degree. F., depending on elevation. The walls of the sealed container act as insulating barriers with respect to heat flow. Thus, the temperature of the lenses and saline solution inside the container rises at a moderate and ever-decreasing rate from ambient (the temperature of the lenses, saline solution, and container at the start of the asepticising cycle) towards the temperature of the steam or boiling water. The presently-used devices which create the steam on the outside of the container are designed and constructed to shut themselves off automatically before the temperature inside the lens-holding container reaches 212.degree. F. The walls of both the lens-holding container and of the steam-generating vessel are only fair (not good) insulating barriers to heat flow. Thus, after the steam-generating unit has been automatically shut off, heat flows out from the lenses and saline solution. The temperature of the lenses decreases at a moderate though ever-decreasing rate towards ambient. This method of asepticising soft contact lenses subjects them to a temperature of less than 212.degree. F. as a peak temperature. Also the lenses are maintained at temperatures near this peak temperature for only a short period of time. When used at places of high elevation above sea level and/or conditions of low ambient temperature, this method of asepticising soft contact lenses fails to subject them to a high enough temperature, sustained for a sufficient duration, to kill many of the pathogenic microorganisms with which they may become contaminated. Also, since these present devices which use heat do so by boiling water in an unsealed vessel, they provide an opportunity for injury to anyone who may be contacted by the boiling water or steam during their operation.